1. Field of the Invention
The present invention relates to a fuel fill tube provided with a leaded fuel restricting shutter which opens in the vicinity of a fuel fill neck during supply of fuel, the shutter serving to prevent unleaded fuel from being supplied into a fuel tank by mistake, and to a vaporized gas recovery system with a bypath passageway adapted to prevent fuel vapors in the fuel tank from being discharged into the atmosphere, as well as a valve disc for discharging such vapors. More particularly, the invention relates to an improved fuel fill tube equipped with a so-called "on board vapor recovery system" in which gasoline vapors are processed on the automobile side.
2. Description of the Prior Art
A fuel fill tube for an automobile is provided with various members such as a valve member and a sealing member at a portion thereof in the vicinity of the fuel fill neck and this comprises the "on board vapor recovery system". Examples of such a system are disclosed in Japanese Utility Model Laid-Open No. 61-125829, Japanese Utility Model Laid-Open No. 61-127024 and U.S. Pat. No. 4,630,749. As can be clearly understood from these prior arts, it has recently been common practice to adopt a structure in which fuel vapors are introduced into a carbon canister through a venting circuit specially provided for the purpose of preventing fuel vapors in the tank from polluting the atmosphere when fuel is being supplied into a tank, and it has been the practice in many cases to locate a selective valve for introducing the fuel vapors into the carbon canister in the vicinity of the fill neck. The construction of this kind of automobile fuel fill tube in the vicinity of a leaded fuel restricting shutter is not so simple as that of conventional fuel fill tubes. The structure is complicated and includes various kinds of members which, because they are not easy to attach to the fuel fill tube, inevitably involve certain problems concerning the order of attachment, the difficulty of rust-proof processing, and thermal influence upon and soiling of inner sealing rubbers, plastic members and so on during attachment or finishing processes.